Electrical power networks are used for transmitting or distributing electric power to user sites, such as industrial plants, office premises and households. Electrical power networks comprise electric stations, which may comprise one or more transformers to transform a voltage level of the electric power either to a lower voltage level applicable for distribution of electric power to user sites or a higher voltage level applicable for transmission of electric power from the electric energy production plants. Electrical power networks further comprise electric power lines to transmit or distribute the electric power. The number of electric power lines connected to a single electric station may vary. Disconnector stations may be located at different locations in the electrical power network for providing a possibility to change the electrical power network topology for example during different faults or varying electric power consumption situations for optimizing the operation of the electrical power network.
Intelligent electrical power network control and/or protection devices may be used at the electric stations for monitoring, protecting and/or controlling the operation of the electrical power network, i.e. the electric power lines and equipment connected to it, against different faults or abnormal operating situations. The same kind of intelligent electrical power network control and/or protection devices may also be used at disconnector stations. Intelligent electrical power network control and/or protection devices, in turn, comprise a different kind of units to carry out necessary electrical power network monitoring, protection and/or control procedures.